The present invention relates to an apparatus and a system for monitoring automatic transmission fluid in an automatic transmission system of a land motor vehicle and in an automatic transaxle system of a land motor vehicle. The apparatus and system are used for the purposes of maintenance and/or repair and serve as a diagnostic tool to the operator or the driver of the motor vehicle while the vehicle is in operating condition.
Contemporary land motor vehicles have at least three systems or a system of components for their operation. These include:
1) a power plant, which may be an engine or a motor;
2) a transmission system, which may be a manual or an automatic shift system; and,
3) wheels, which conventionally are four in number.
An internal combustion engine is the most popular and commonly used component of a power plant in land motor vehicles. The internal combustion engine may be fueled by gasoline, diesel oil or natural gas or propane. Monitoring apparatus is coupled to the power plant and is, usually, located on the vehicle""s dashboard, which provides an ongoing display of engine operation data for the operator or the driver of the motor vehicle, while the vehicle is in motion. The dashboard serves as an indicator for various engine data outputs and malfunction indications arising out of engine operation, if any. The engine operation data may be used to diagnose the health or condition of the power plant, during its operation. Other, more sophisticated monitoring apparatus, which may be coupled to the power plant on a temporary basis, may be used for a more detailed diagnosis, maintenance and/or repair of the power plant.
The automatic transmission system and the automatic transaxle system used on land motor vehicles are similar, in many respects. The automatic transmission system predates the automatic transaxle system. The most obvious difference between the two systems is that the automatic transmission system, while coupled to the power plant, includes final drive gears, a drive shaft and differential gears. The drive shaft remotely separates the final drive gears from the differential gears. The automatic transaxle system is, also, coupled to the power plant and includes the final drive gears and differential gears. All gears are intrinsic parts of the system. Automatic transmission systems are used on four-wheel drive and on rear-wheel drive land motor vehicles. Automatic transaxle systems are used on front-wheel drive land motor vehicles.
There are further similarities to the automatic transmission system and the automatic transaxle system. When the engine is in operating condition, both systems convert engine""s torque into rotational power that drives the wheels of the vehicle. Both systems shift gears automatically according to the engine output power and speed. Both, also, use a hydraulic sub-system for changing gears and the hydraulic fluid of the hydraulic sub-system for lubricating contacting elements of the system. Although lubricated, there is a friction between the contacting elements in both systems and, because of that friction, the systems tend to heat up during operation. The systems use hydraulic fluid in the hydraulic sub-system to cool the systems. The hydraulic sub-system includes a cooling stage for cooling the hydraulic fluid. The cooling stage of the hydraulic sub-system includes a pump, for circulating the hydraulic fluid, and a cooling core or a radiator, through which the hydraulic fluid passes. The cooling core or the radiator serves to reduce the temperature of the hydraulic fluid. The hydraulic fluid, generally used in the hydraulic sub-system, is referred to as automatic transmission fluid (referred to as xe2x80x9cATFxe2x80x9d). In a healthy automatic transmission system and a healthy automatic transaxle system, the operating temperature and operating circulation pressure of the ATF are maintained within predetermined values.
U.S. Pat. No. 5,700,226 to Droste teaches a system for providing an adequate volume of lubrication fluid to all mechanical components of an automatic transmission system and for producing that flow in a manner consistent with the operating requirements of the automatic transmission system. Inherent in the teaching of Droste is the vital importance of the condition of the ATF, the temperature of the ATF and circulating pressure of the ATF in the automatic transmission system. The Droste disclosure, however, does not mention the automatic transaxle system. The ATF, which is used in the hydraulic circuits and for lubrication of mechanical components in both the automatic transmission system and the automatic transaxle system, should be maintained at some predetermined level. Moreover, functionality of ATF requires certain operating temperatures, which have been determined by the manufacturer and/or designer of the system. In addition, for proper operation of the automatic transmission system, the ATF, in an operating transmission system, should be maintained within some predetermined pressure range, as determined by the manufacturer and/or designer of the transmission system.
For clarity and conciseness, hereinafter the terms automatic transmission and/or automatic transmission system shall include the automatic transmission system and the automatic transaxle system.
There are three major functions of the ATF in the automatic transmission system of a motor vehicle:
1) It serves as a hydraulic fluid for moving components of the automatic transmission system;
2) It serves as a lubricant for moving components of the automatic transmission system; and,
3) It serves as a coolant or heat transfer fluid for removing heat from the automatic transmission system, including its moving components and other parts of the automatic transmission system.
All of these functions place the ATF under a great strain. To accomplish this multi-use of the ATF, the hydraulic sub-system of an automatic transmission system includes:
1) Circulation of the ATF, via a hydraulic pump, through hydraulic circuit channels and the lubrication channels for lubrication;
2) Movement of components of the automatic transmission system to produce automatic shifting;
3) Cooling the components of the automatic transmission system and circulating the
ATF through a heat transfer device to remove heat from the ATF.
Using ATF, as a lubricant and a coolant fluid, drives it to high temperatures, which are substantially higher than the recommended operating temperatures of the ATF. The ATF must be cooled. Cooling the ATF is accomplished by circulating it at some rate through a heat exchange unit, such as a radiator. To produce an adequate heat exchange, the circulation rate of ATF or the ATF""s pressure in the system depend on the size and efficiency of the heat exchange unit and the heat coefficient of the ATF. This essentially requires a constant flow, at some predetermined rate, of the ATF through the automatic transmission system, including the cooling channels of the heat transfer elements of the radiator.
The object of the present invention is to provide a system for monitoring of automatic transmission fluid""s characteristics in an automatic transmission (or transaxle) system of a land motor vehicle for maintenance and/or repair.
Another object of the present invention is to provide a system for monitoring of automatic transmission fluid""s characteristics in an automatic transmission (or transaxle) system of a land motor vehicle for the operator or the driver of such motor vehicle, while the vehicle is in an operating condition.
The present invention provides an automatic transmission system hydraulic fluid characteristic monitoring system. Invention""s components are conventionally well known to one skilled in the art and, thus, may be obtained. However, the unique combination of those components is not known. The invention provides a fluid sensor, mounted in a circulating channel of the ATF, located in the flow path of the ATF. The fluid sensor detects and monitors the presence of the ATF, the flow rate of the ATF in the circulation system and the pressure of the ATF, and, optionally, the temperature of the ATF. The data sensed by the fluid sensor from within the flow path of the ATF is applied to a microprocessor, which analyzes the data and outputs the information to a readout, connected to the microprocessor, displaying the data, preferably, in digital form. From the readout, an analysis of the health of the circulation sub-system and the ATF in the sub-system may be made. Moreover, the readout will serve as detection tool for problems affecting the automatic transmission system.
The present invention may be used as a maintenance and/or repair tool for the automatic transmission system. The invention is used for detection of blockages and/or restrictions created in the components of the circulation stage of the hydraulic sub-system, including the output of the pump component and functional irregularities in the moving components of the automatic transmission system, interfering with the ATF""s circulation.
Moreover, the present invention provides an on-going monitoring system of the ATF flow in the automatic transmission of the motor vehicle. The invention, having a readout component, displays data on the dashboard of the motor vehicle. The data is displayed on the dashboard while the motor vehicle is in motion or being repaired. By viewing the readout data, the driver or the operator of the motor vehicle may analyze the status and the health of the automatic transmission system, while the motor vehicle is moving, and, thus, act accordingly, if there are any deviations from the normal operating conditions.